Method of producing photographic dyestuff images



May 26, 1936. B. GASPAR 2,042,253

METHOD OF PRODUCING PHQTOGRAPHIC DYESTUFF IMAGES Filed Feb. 14, 1953SILVER HA /DE:

EMULSION --,IEAW FILM EXPOSED DIFFUSELY COLORED SUPPORT \v DIFFUSELYCOLORED v MErALL/c SILVER IMAGE -.f- I

DEVELOPED-AND FIXED LAYER FREE FROM SILVER REST OF THE \SILVER IMAGEDYESTUF'F' LOCALLY oEsr/a'avL-o. -Pma'r br THE SILVER COIVSUMED DYESTUFFIMAGE SILVER con VERT'ED SILVER CHLORIDE IN SILVEE HLORIDE.

DYESTUFF IMAGE SILVER CHLOE/DE REMOVED BY FIX/N6.

DYssruFF IMAGE Patented May 26, 193 v ma-moo or raonuomc .rno'rocaarmc Ix DYESTUFF nuaces Gaspar, Brussels, Belgium Application February 14,1933, Serial No.'656,'l63 In Germany February 15, 1932 4 Claims. (01. 95-2) This invention relates to a methodof producing photographicdyestuifimages.

The figure is a flow sheet setting forth the steps of. the method.

Heretofore I have used methods according to which a diffuselycoloredmetallic silver image is ,treated in an agent which destroys thedyestufl at the points, of the silver image in proportion to'the amountof silver present. The quantity of silver is a governing factor asregards the destruction of the dyestufl. In thisconnection, an agent isemployed which simultaneously dissolves away the amount of silverpresent, and any residual quantities remaining are dissolved out in thesubsequent reducing bath. The greater part of the silver,,however, isdischarged simultaneously in the dyestufl-destroying bath;

Now it has been found that as regards bril liance and graduation of the.dyestufl images considerably better results may be obtained if initiallythere is employed a much morepowerful silver:

image, i.,e., if a relatively large deposit of silver is present rightfrom the start in the photographic emulsion, as compared with the amountwhich is necessary to participate in the destruction of the dyestuif.The reason for this behaviour resides partly in the fact that in thismanner it is possible by reason of these amounts of silver to performoperations which/conform with the straight portion of the characteristiccurve of the photographic emulsion. It is also possible by this processto obtain clear and distinct images in a considerably shorter time thanif a silver image is employed which contains merely the exact amount ofsilver necessary for destruction of the dyestuif or merely a slightquantity in excess thereof. In following this course, there will beconsumed at practically all points of the image merely a small quantityof the silver present for assisting in the local destruction of thedyestufl simultaneously present in the layer. There is, however, alsoobtained the additional advantage that very good dyestufl or reversedimages may be obtained, as in this connection the duration of treatmentin the bath may be maintained constant to a very large extent. Thisperiod of treatment may be determined very readily in one singlepreliminary test, .if the color of the layers (as is always the caseparticularly in connection with sensitized materials coloured in theemulsion) is approximately the same. In the case of multi-layer imagesit is particularly important in accordance with the invention to employa relatively large proportion of silver for performing the methodaccording to the invention, as

PATENT OFFICE" the eflectiveness of the bath decreases with increasingdepth of layer, so'that the period of treatment of thedyestufi-destroying agents would in the case of a plurality of silverhalide layers poured one on to the other be relatively iilong, whenusing a normal quantity of silver. The increased quantity of silver isobtained by known means by corresponding exposure and development. o

' The constant and brief period of treatmentin 10 thedyestuif-destroying bath is of particular importancein connection withmechanical treatment of kinematograph films, in order to always arriveat equal results. In connection with films sensitized on both sides, itis also important to II employ a surplus quantity of silver, as byreason the silver has also been 'dissolved'away,.and, as

may readily be determined by a preliminary test;

a constant period of treatment on the part of $5 the dyestufl-destroyingagent is to be expected. The use ofthis method also offers particularadvantage in connection with layers, which contain a plurality ofdifferently colored particles in adjacent or superimposed disposal.

It is possible to employ the dyestufl discharg ing bath, which destroysthe dyestuff at the points of the silver deposit or at the points freeof silver by oxidation or reduction.

This method may also be made use of in the 35 additional treatment ofsensitized materials containing dyestuflf-forming substances. The dissolution of the silver takes place in a desired reducing bath. For thispurp0se, there may be found, however, that merely neutral'reducers, orreducers which do not exert a vigorous action may be employed, i. e.,which do not act on the dyestufl image in such manner as to vary thesame.

It has been found that the majority of photographic reducing baths actonly on the layer in a mannernot adapted to vary the dyestufl if alltraces of the dve'stufl-destroying bath are removed as a result ofverythorough rinsing:

It has furthermore been observed that the extremely powerful sensitizingof the fast, direct or acid dyestufis, and more particularly azodyestufls, is maintained even with traces of the dyethe images have beenwell washed. It has been. o

stun-destroying agent containing thioureas or substituted thioureas. Thefast nature of the dyestui! may be very considerably increased inadvantageous fashion without lengthy washing and without endangering.the dyestuil image itself, if a reducing agent is employed containingcopper. This bleaching bath is moreover particularly rapid, and veryeffective either in the case of photographic materials, which contain aplurality of diflerently colored layers, poured one upon the other, or aplurality of differently colored particles in superimposed or adjacentdisposal in one layer, whereby the vigorous and rapid bleaching outaction is not accompanied by a dyestuil' discharging efl'ect, agents.

According to the invention employed oi the followingcomposition.

Cupric sulfate grammes 20 Sodium chloride grammes 20 Nitric acid -ccm. 1Water grammes or Grammes Cupric chloride -i '30 Nitric acid 1 Water 100The images proceeding from the dyestuif-destroying bath are rinsedbriefly and additionally treated in one of the baths above referred tofor the purpose. of-bleaching out the silver image, which operation isusually completed in 1 to 2 minutes, whereupon the images are immersedfor 30 seconds in a 20% fixing sodium solution, whereby the silverchloride formed is dissolved away. Washing isthereupon again'eil'ectedfor a brief period. The images thus produced are of an ex cellent kind,fast in color, and also remarkably resistant to washing.

I claim:-- 1. A method of producing photographic dyestuil imagesinphotographic layers, which are colored with dyestufls or containdyestuif-forming substances in the emulsion, which consists in initiallyproducing by exposure and develop-f as in the case of other reducing areducing agent is ment an'image having an amount of silver in excess ofthat normally required for the destruction of the dyestui! andsubsequently subjecting the image to a dye-destroying bath wherein apart of the silver assists in the destruction of the dyestufl, thensubjecting the image to a dye-destroying bath surplus silver bysubjecting the image toa bath containing weak reducer.

3. A method of producing photographic dyestufl images in photographiclayers, which are colored with dyestuffs or contain dyestuir-formingsubstances in the emulsion, which consists in initially producing byexposure anddevelopment an image having an amount of silver in excess ofthat normally required for the'destruction of the dyestuii', thensubjecting the image to a dyedestroying bath wherein a part of thesilver aids in the dyestuif destruction, and subsequently removing thesurplus silver by subjecting the image to a bath containing a cupricsalt to obtain a rapid bleaching out action without a dyestufldischarging effect.

4. A method of producing photographic dyestuil' images in photographiclayers, which are colcred with dyestufls, which consists in initiallyproducing by exposureand development an image having an amount of silverin excess of that normally required for the destruction of thedyewherein a part of the silver aids stuff, then subjecting the image-toa dyestui! destroying bath, rinsing the image in a bathcontaining acupric salt to form a silver halide, next immersing the'image ina'flxing solution to wash away the silver halide, and subsequentlywashing the image for a brief period to produce the final image.

destruction, and subsequently re- Bans assess;

